*-þuz

From Proto-Indo-European *-tu-s, a proterokinetic masculine action-noun suffix. PIE *-tu- was one of the major verbal abstract/action-noun suffixes, but its reflexes often developed a more concrete or resultative sense than the similar feminine *-ti-s formations (Krahe & Meid 1969: 151–52; Luraghi 2009: 5–6; Ringe 2017: 74). The suffix assumed different forms based on the final consonants of the base: after -f, -s, and -h, the t- remained unshifted; it was also subject to Verner's Law if the original accent was on the suffix, in which case the t- became a d- (Lehmann 1986a: §4.2.1); compare *ferþuz and *furduz < PIE *pér-tu-s ~ *pr̥-téw-s. Cognates include Latin -tus -tus, Lithuanian -tus, Sanskrit -तु (-tu), and Ancient Greek -τύς (-tús), all forming action nouns.